This may be true for some specific US states, but declaring it wholesale true in the US is wrong. From the ATF FAQ on homemade firearms:
You do not have to add a serial number or register the [privately manufactured firearm] if you are not engaged in the business of making firearms for livelihood or profit.
This may be true for some specific US states, but declaring it wholesale true in the US is wrong. From the ATF FAQ on homemade firearms:
Removed by mod
I apologize for replying to what you wrote, and for not having future knowledge that you were going to edit your comment.
Super uncivil reply